1. Field of the Invention
The invention relates to new (p-aminohydroxyphenyl)acrylamide derivatives and dyeing agents containing these compounds for dyeing keratin fibers, particularly human hair.
2. Description of the Related Art
In the area of keratin fiber dyeing, particularly hair dyeing, oxidation dyes have attained substantial importance. In this case, the coloration is produced by reaction of certain developers with certain couplers in the presence of an appropriate oxidant. Suitable developers are, in particular, 2,5-diaminotroluene, 2,5-diaminophenylethyl alcohol, p-aminophenol, 1,4-diaminobenzene and 4,5-diaminopyrazole-1-(2′-hydroxyethyl)-pyrazole, and suitable couplers are, for example, resorcinol, 2-methylresorcinol, 1-naphthol, 3-aminophenol, m-phenylenediamine, 2-amino-4-(2′-hydroxyethyl)aminoanisole, 1,3-diamino-4-(2′-hydroxyethoxy)benzene and 2,4-diamino-5-fluorotoluene.
The oxidation dyes used for dyeing human hair must meet numerous requirements in addition to that of being able to produce colorations of the desired intensity. For example, these dyes must be harmless from a toxicological and dermatological standpoint, and the hair colorations obtained must have good light fastness, resistance to permanent waving, acid fastness and rubbing fastness. In any case, however, in the absence of exposure to light, rubbing and chemicals, such colorations must remain stable over a period of at least 4 to 6 weeks. Moreover, by combining appropriate developers and couplers, it must be possible to create a wide range of different color shades.
To attain natural and, in particular, fashionable color shades in the red region, p-aminophenol, alone or in admixture with other developers, in combination with suitable couplers, is primarily used. Attempts have already been made to improve the properties of p-aminophenols by the introduction of substituents. In this regards, the reader is referred to German Unexamined Patent Application DE 196 07 751 which describes colorants containing as developers special substituted p-aminophenol derivatives, for example 5-amino-2-hydroxycinnamic acid.
With the currently known colorants, it is not possible, however, to meet the requirements placed on colorants in all respects. Hence, the need continued to exist for new developers capable of meeting the aforesaid requirements to a particularly high degree.